| Latticed shell has characteristies of great rigidity,light dead weight,magnificent structure, forced reasonable, great coverage and good synthetic technology index. It is a large-span spatial structure which has been gotten great concern by home and abroad, and also has broad development prospects. In recent years, domestic scholars has gotten many achievements on the field about static and dynamic performance and seismic study of latticed shell. However, most of these research achievements are made separately on consideration of lower support-system and upper latticed shell, imitate the support of latticed shell with simply supported or fixed supported, and then independently mechanical analysis. In fact,most shell structures based on support-frame,seismic load is transfered to support-frame through ground motion,and then to latticed shell through support-frame.If researching seismic performance of spatial structure without considering the effects of supporting structure, the result will be great betray with actual situation. Therefore, the research of dynamic analysis of latticed shell with the effects of supporting structure under earthquake effects has great importance.Combination of recent references, this paper considerate single-layer cylinderical latticed shell, use nonlinear finite element theory and finite element analysis tool ANSYS, combining shell roof with supporting structure as an integer to analysis.First of all,set up modal,considering three supporting conditions:first one, the same as predecessors,simplify the lower part of supporting structure as fixed hinge; second one, human-shaped column supporting at the two longitudinal edges; the third,one side fixed hinge supports and another side column support. Check latticed shell's dynamic characteristic under three-dimension earthquake ground motions about these three supporting conditions, considering influence of vary in parameter,such as span, rise-span ratio,earthquake loads and length to span ratio. Comparative analysis of these three structures,and get the conclusion that the way of supporting at the two longitudinal edges will reduce the stiffness of direction Y and Z,increase the dynamic response of both directions,the axis force of element about arch camber direction also grows heavily; the dynamic characteristics of latticed shell structure is impacted apparently by high-order vibration mode. Dynamic failure mechanism of shell structures under earthquake loads were studied to research dynamic behavior and failure modes.Based on the comparison can obtain several results:the modes of single-layer cylindrical latticed shell with fixed hinge supports belongs to strength failure, while the failure modes of shells with column supports have the features of dynamic instability,belong to the combination of strength failure and dynamic instability,focus on strength failure.Then, push-over analysis of latticed shell by using structural analysis tool SAP2000, and for the seismic performance evaluation. |
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